XXHighEnd

Might you be confident in making a backup from the Registry easily and/or fast, maybe do so (a Restore Point which you will be able to really use when necessary). If all is right this is not necessary, but better be safe than sorry.

0.9z-6 and up will automatically degrade your OS to near to numb, while you will still be able to fairly normally use it (even during playback). The  "tweaking" has been setup so, that whatever you tweaked yourself in advance of XXHighEnd will be utilized and consistently be restored to your likings and when you want.

Have that backup ready ! ... and ...
Use at your own risk !

As we know the best sonic qualities are achieved by means of the so called Unattended Playback, that meaning that there will be no GUI left to interfere. In the mean time all what is not necessary is shutdown from the Operating System, and playback is on its own. Still, all control is there by means of keyboard shortcuts (like Next Track, Change Volume), and while some "stealth" players intend to start off like this to your not-so-inconveniency, XXHighEnd allows you to bring up the GUI whenever you want for even more control (like selecting new albums etc.), that by itself only temporarily interfering the sonic performance.

In addition to this, with Minimize OS the OS is dynamically tweaked to-completely-death, referring to the ever back topic where all may have started. To some small extend that was. However, the "dynamically" in this case means that the OS is reconfigured on the spot, and that now a reboot will cause this reconfiguration to be permanent.

Let the difference be clear : What happened before (and what other so called stealth players do with cMP as the exception), is nothing much different from what XXHighEnd always did; kill all what can be killed and next commence playback ("Waiting for Services to stop"). This is nice, but far from optimal. "Nice" for it really helping, but without a clue of all what was running and keeps on running. This is actually so bad that now even a totally incapable laptop will become a "real machine".

As told, you can just keep on using the PC during playback, and although maybe not optimal for SQ, you will see the gain in overall speed of everything once the OS has been set to be quite dead. You'll love already that part.

Might you become fedup with the speed, there's a single button in XXHighEnd which will revert all to normal, and which only takes that reboot (automatically performed). In the next 30 seconds you will be back to what Gates aver imagined.
And oh, when you like that better anyway, don't use this button, and all will be as usual and known from XXHighEnd. But remember, far from optimal.
This button is under the right pane and is called "Minimize OS" (shown in the active state below).

(http://www.stordiau.nl/XXHighEnd/MinimizeOSButton02.png)

Let it also be known that all kind of mixed modes are possible, like using XXHighEnd in normal Attended Fashion (which really shouldn't be called "normal" as such), while in the mean time the OS is still that dead body.

This is not for XP, and most probably this can not be checked for properly !  (hence prevent you from attempting it)